Dr. Syed Moin Hassan was riled up. "I don't know who needs to hear this," he posted on Twitter, "BUT YOU ARE NOT LAZY IF YOU ARE WAKING UP AT NOON." Hassan, who is the Sleep Medicine Fellow at Brigham and Women's Hospital in Boston, speaks to Short Wave's Emily Kwong about de-stigmatizing sleeping in late, and why a good night's rest is so important for your immune system. Email the show at shortwave@npr.org.